Known propulsion systems for ships are, for example, inboard and outboard transmission systems. An inboard transmission system includes an engine arranged in the hull. A drive shaft is connected to the engine through a reduction gear, with the drive shaft passing through the ship's hull and featuring a drivable propeller at its end for propulsion of the ship. The propeller directs its flow towards the rudder. For realization of desired maneuvers, the rudder is controlled by a steering arrangement, with several rudders normally being provided, for example, relative to the longitudinal axis of the ship, a starboard-arranged rudder, and a port rudder.
Furthermore, an electronic steering mechanism arrangement for the ship's rudder is known as a steer-by-wire system. This system involves replacement of mechanical or hydraulic connections between the steering wheel and the rudders with an electronic control device and a suitable network for transmitting the corresponding signals. The electronic control device receives signals from a sensor which detects the steering-wheel position and converts them into output signals for triggering the electric actuator of each rudder and setting of a steering angle. For example, two inboard transmission systems that are arranged on a starboard rudder and a port rudder of the ship can be used.
It has been shown that when a ship is driving straight ahead, the toe angle of both rudders or their relative position to one another considerably influences the resistance to flow. With known control devices, a multitude of test runs is required in order to determine manually a toe angle in relation to the characteristic parameters of each ship. It is not possible to continually check when these known arrangements are used.